De novo-derived cationic antimicrobial peptide activity in a murine model of Pseudomonas aeruginosa bacteraemia

Abstract

Objectives: We describe the antimicrobial activity against Pseudomonas aeruginosa of the de novoderived antimicrobial peptide WLBU2 in an animal model of infection.Methods: For this study, an intravenous (iv) model of P. aeruginosa infection was established. The minimum lethal murine dose of P. aeruginosa strain PA01 was determined to be 3 3 10 7 cfu when bacteria were administered iv. Increasing concentrations of WLBU2 were instilled either prior to or following PA01 septic exposure.Results: For the mice given peptide post-bacterial infection, in the 1 mg/kg group, nine of nine animals died because of Pseudomonas sepsis; in the 3 mg/kg group, only one of nine succumbed to infection and in the 4 mg/kg group, all mice were protected (P < 0.0001). Similar results were obtained when WLBU2 was given 1 h prior to Pseudomonas infection. Conclusions:Although the therapeutic window in this model is narrow, the results nonetheless provide encouraging evidence for WLBU2 as a potential prophylactic or treatment of bacterial infection.

Rational Design of Engineered Cationic Antimicrobial Peptides Consisting Exclusively of Arginine and Tryptophan, and Their Activity against Multidrug-Resistant Pathogens

“…Previous studies of the eCAP WLBU2 indicate that mammalian cytotoxicity at high micromolar concentrations (up to 100 M) is considerably depressed in human serum and whole blood, whereas bacterial killing was still observed at low micromolar concentrations (46,53). These observations, although requiring further studies for generalization, suggest that it is essential to look at cytotoxicity or antimicrobial selectivity in appropriate physiologically relevant environments.…”

“…It has become increasingly clear that, in the context of this cationic amphipathic motif, there are unique, evolution-tested (70), primary amino acid sequences that determine the specificity of microbial targets and environments (23,46,47,53,(71)(72)(73). The idea of using Arg as the component of the hydrophilic face of a peptide stems from our studies of conservation of Arg in lentiviral lytic peptides of HIV-1 combined with the fact that Arg retains its positive charge in the most basic physiological environment.…”

“…Further, Trp substitution into the LBU sequence significantly enhanced activity against both Gram-positive and Gram-negative bacteria in environments that are considered challenging to AMPs, such as saline, serum, and whole blood (46,47). In fact, systemic administration of the most potent of the LBU derivatives (WLBU2) resulted in complete protection of mice injected intravenously with a lethal dose of P. aeruginosa with no obvious harmful side effects (53). Based on these and other studies of Trp-rich AMPs (e.g., indolicin and tritrpticin) (43,49,50,(54)(55)(56), we reasoned that the membrane perturbation properties of Arg and Trp, presented in the context of an optimized amphipathic helix, can be further exploited to engineer shorter and more highly potent eCAPs, thereby reducing the cost of production.…”

The Antifungal Vaccine Derived from the Recombinant N Terminus of Als3p Protects Mice against the BacteriumStaphylococcus aureus

“…Staphylococcus epidermidis 35984 (4,8) and Enterococcus faecalis TX2484 (vancomycin resistant) (3) are clinical bloodstream isolates also known to cause lethal infection in animal models at high inocula. Pseudomonas aeruginosa PA-01 is a clinical wound isolate (33) known to cause lethal infection in animals (9). All bacterial isolates were grown overnight in a shaking incubator in brain heart infusion (BHI) broth at 37°C, passaged until log-phase growth, prepared for inoculation by using the optical density (OD) with confirmation of the inoculum by colony counting, and washed in phosphate-buffered saline (PBS) prior to inoculation in 0.5 ml of PBS.…”

Covalent immobilization of antimicrobial peptides (AMPs) onto biomaterial surfaces

“…These are distinct from those in nature, with simpler but rationally engineered composition, obtained by varying the amino acid content and sequence and overall peptide length to achieve enhanced activity and very low cytotoxic properties [57]. For example, Mietzner and co-workers [58][59][60][61] have developed a series of de novo peptides based on structure-function properties observed in natural AMPs. They engineered the peptide composition to achieve enhanced potency, selectivity and stability.…”